01 - Heat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together all-purpose flour, whole wheat flour, sugar, baking soda, and salt.
03 - Stir in dried cranberries and chopped walnuts until evenly distributed and coated with flour.
04 - In a separate bowl, whisk together buttermilk, melted butter, and egg.
05 - Pour wet ingredients into dry. Mix gently with a wooden spoon or hands until a shaggy dough forms, avoiding overmixing.
06 - Turn dough onto a lightly floured surface. Shape into a round loaf approximately 7 inches in diameter.
07 - Place loaf on the prepared baking sheet. Using a sharp knife, cut a deep X on top. Brush surface lightly with buttermilk.
08 - Bake for 35–40 minutes until golden brown and a skewer inserted into the center comes out clean.
09 - Transfer to a wire rack and allow to cool for at least 30 minutes before slicing.